1. Field of the Invention
The present invention relates to a liquid infusion apparatus and, more particularly, relates to a liquid infusion apparatus for infusing liquid by pushing a plunger into a syringe.
2. Description of the Prior Art
FIG. 1 shows a conventional liquid infusion apparatus. In FIG. 1, reference numeral 1 denotes a CPU, 2 denotes a processing circuit of a signal from an incremental linear encoder, 3 denotes a synchronous pulse motor, 4 denotes a reduction gear, 5 denotes a feed screw, 6 denotes a carriage, 7 denotes a pushing holder fixed to the carriage 6, for pushing a plunger 9 of a syringe 8, 10 denotes a processing circuit of a sensing signal from an established position detecting sensor 13 positioned at a remaining infusion liquid quantity small section, 11 denotes an elongated opaque plate with fine slits for forming an incremental linear encoder, arranged in parallel to the feed screw 5, 12 denotes a photo-coupler mounted on the carriage 6 for detecting pulses from the incremental linear encoder, 14 denotes an established position detecting dog connected to the carriage 6, 15 denotes an instruction pulse counter for counting instruction pulses to the pulse motor 3, 16 denotes a pulse counter for counting pulses from the incremental linear encoder, and 17 denotes a driving circuit for the synchronous pulse motor 3.
In such conventional liquid infusion apparatus, an output from the photo-coupler 12 is applied to the pulse counter 16 through the processing circuit 2, and an output from the established position detecting sensor 13 is applied to the CPU 1 through the processing circuit 10. The pulse counters 15 and 16 are monitored and managed by the CPU 1.
The driving circuit 17 receives from the CPU 1 instructions indicating a distance to be moved by the motor 3 and a speed etc. of the motor 3, and drives the motor 3. The carriage 6 is moved by the motor 3 through the reduction gear 4 and the feed screw 5. A pulse signal generated by the incremental linear encoder and picked up by the photo-coupler 12 is processed by the processing circuit 2 and sent to the pulse counter 16 as a moving information of the carriage 6, so that the motion of the carriage 6 is monitored directly by the CPU 1.
A value of the moving instruction recognized by monitoring the instruction pulse counter 15 per unit time is compared with an actual moving distance recognized by monitoring the encoder pulse counter 16, so that a correlation state between the value of the moving instruction and the actual moving distance can be detected.
If the correlation state is maintained, it is recognized that the pushing holder 7 is moved correctly according to the instruction.
The output from the established position detecting sensor 13, which is generated when the established position detecting dog 14 mounted on the carriage 6 passes across the established position detecting sensor 13 during the liquid infusion operation, is processed by the processing circuit 10 and sent to the CPU 1 as a position information. When the position information from the established position detecting sensor 13 is applied to the CPU 1, a counted value in the instruction pulse counter 15 is memorized in the CPU 1, or the pulse counter 15 is reset by the CPU 1. Then, instruction pulses sent from the driving circuit 17 to the synchronous pulse motor 3 are counted by the instruction pulse counter 15. Each of the instruction pulses sent to the motor 3 corresponds to a distance moved actually by the pulse motor 3, so that the absolute position of the pushing holder 7 and thus the absolute position of the plunger 9 engaged with the pushing holder 7 can be recognized by counting the instruction pulses sent to the motor 3 by the instruction pulse counter 15.
In such conventional liquid infusion apparatus, the absolute position of the pushing holder 7 can be recognized after the established position detecting dog 14 is passed across the established position detecting sensor 13 during the liquid infusion operation by counting the pulses sent to the pulse motor 3, so that information about the warning for the remaining infusion liquid quantity small section, and information about the finish of the liquid infusion operation can be obtained.
Further, in the conventional liquid infusion apparatus, operation steps, such as the start and stop of the liquid infusion operation are indicated by the LED or liquid crystal. The erroneous operation can be informed by a sound of beep or melody.
In the above described conventional liquid infusion apparatus, however, the absolute position of the pushing holder 7 can be recognized only when the established position detecting sensor 13 is detected by the established position detecting dog 14 during the liquid infusion operation by the motor 3 driven by the instruction pulses. Accordingly, the information about the finish of the liquid infusion operation cannot be obtained when the liquid infusion operation is started.
Further, the operator cannot recognize the kinds of error even if the sound of beep or the melody is generated. Accordingly, the operator has to approach the small indicator of the liquid infusion apparatus in order to recognize the contents or kinds of the warning and it is troublesome.
In order to solve the forgoing problems in the conventional liquid infusion apparatus, it is an object of the present invention to provide a liquid infusion apparatus comprises a pushing holder for pushing a plunger into a cylinder of a syringe, a pulse motor for moving the pushing holder, an incremental linear encoder having a plate with slits arranged along a moving direction of the plunger and a position detecting device moved together with the pushing holder, counting means for counting encoder pulses from the encoder, means for counting instruction pulses to the pulse motor, and a first sensor, the mounting position of the first sensor being recognized as a counting number of instruction pulses to the pulse motor, wherein the first sensor is arranged along the plate with slits at a portion between a position where the pushing holder is connected to the plunger for the liquid infusion, and a start position where the pushing holder is separated from the plunger, wherein the counting means is reset when the first sensor is detected by the position detecting device, and started to count the encoder pulses according to the movement of the pushing holder, and wherein a time to complete the liquid infusion is calculated by using a distance between the position where the plunger is connected to the holder and a liquid infusion finish position proper to the syringe, and a predetermined liquid infusion speed, and displayed.
Another object of the present invention to provide a liquid infusion apparatus wherein a time to complete the liquid infusion is calculated by using a predetermined liquid infusion speed and a distance between a present position of the holder and a liquid infusion finishing position proper to the syringe determined previously, and displayed, the present position of the holder being obtained by summing a moving distance recognized as the count number of the instructing pulses to be sent to the motor and a position of the holder recognized as the count number of the encoder pulses at the start of the liquid infusion.
Further object of the present invention to provide a liquid infusion apparatus, further comprising at least one second sensor provided along a moving path of the pushing holder for liquid infusion, the position of the second sensor being recognized as a count number of the instruction pulses to the motor, wherein when the second sensor is detected by the position detecting device, the present position of the pushing holder is revised automatically to a position data of the second sensor, and thereafter the position of the pushing holder is determined by using a count number of the instruction pulses to the motor which is more precisely than the encoder pulses.
Still further object of the present invention to provide a liquid infusion apparatus, further comprising a chronometer element which can recognize the present hour, wherein an expected liquid infusion finishing hour can be calculated and displayed by using the present hour and a time to complete the liquid infusion.
Yet further object of the present invention to provide a liquid infusion apparatus, further comprising a sound display device, wherein a time to complete the liquid infusion or an expected finish hour can be indicated by a voice.
Still another object of the present invention to provide a liquid infusion apparatus, further comprising setting means for setting operation orders of liquid infusion, means for indicating the operation orders by a voice, means for comparing actual operation orders with the operation orders predetermined by the setting means, and means for indicating a difference by a voice when actual operation orders are different from the predetermined operation orders.
These and other aspects and objects of the present invention will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following description, while indicating preferred embodiments of the present invention, is given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.